Bikini-clad women got together in Hyde Park to make it clear they don't like being told what kind of body they should have.

Last month, fitness company Protein World managed to aggravate a lot of people on the internet by sticking a diet pill advert all over the London Underground.

"ARE YOU BEACH BODY READY?" asked the neon yellow poster, next to a photo of size six model Renee Somerfield. The implication being that a woman would not be ready for a beach until she looked like Renee, because no one wants to see her disgusting normal body exposed and enjoying itself under the sun.

Cue angry people everywhere defacing the posters with slogans like, "Each Body's Ready" and "Fuck Off," followed by an online petition that has now garnered over 70,000 signatures.

The whole debacle might have blown over had they removed the posters and apologized for the oversight. Instead, their CEO took to Twitter to say, "We are a nation of sympathizers for fatties," asking "Why should your insecurities be our problem?" before pointing out that their sales had gone up.

Fiona Longmuir, a pissed-off blogger, then decided to organize a protest in Hyde Park to make clear the point that anyone with a body is "beach body ready," regardless of their size. This is how we ended up among a crowd of shivering, half-naked people rolling around in the grass with beach balls on a Saturday afternoon.

"This is meant to be a party to celebrate all the different body images that there are and make women feel amazing about themselves," Fiona, the organizer (pictured above, left) told us at the protest.

"The advert was the straw that broke the feminist back, and it just so happened to be for Protein World. After their response on Twitter, I think that it couldn't have happened to a nicer company," she said sarcastically. "Plus, we've had women tweet us saying that we've made them want to buy a bikini for the first time in ten years, and to me that's not a small thing."

Gil (pictured above, left), was one of many men at the protest. "I saw this poster a while back and it was in replacement of the "This Girl Can" posters, which pissed me off. It's also such an aggressive campaign. Diet pills are a big issue with teenagers and eating disorders, so it feels irresponsible," he said.

"As a bloke, I don't feel like I have the same pressures as women. This protest is about increasing awareness and making people feel better about their own bodies."

Alaska (pictured above, right) told us: "This is technically against the Protein World campaign, but it's really about the bigger issue of body image in general. I've got confidence now, but I've had my own issues with eating disorders. I wish when I was younger I'd seen people standing up and doing something about it."

After about 20 minutes of loitering about in swimming garments, Sandy and Sandra from the Channel 4 show Gogglebox turned up, parked a deck chair up in the middle of the crowd and started shouting: "Beach body! Beach body!"

Sandra then told the demonstrators: "I'm curvy, babes. I can't be wearing a bikini, though. I'm fat, right, but I'm not fat! Egg, bacon, sausage, and beans, babes. A fry up is for the body movement."

Then she gave out some free jewelry from her "Rings and Tings" range. I pocketed a chintzy bright purple ring before going to speak to some more protesters. Hannah, who used to work in advertising, told me that she saw the Protein World advert on the tube and was shocked by it.

"The slogan, the heavily photoshopped image and the fact it's for weight loss—are you serious?" she said. "In general, the [advertising] industry is all about building on people's insecurities in order to buy a product that they don't need. That's why I'm not working in advertising any more. That's the ethos behind it, and it's not healthy."

Although most people were there to support the cause, there were two anti-feminist guys were filming the whole thing for their YouTube channel. "I don't think this is a good use of energy as the issue is not important," said James, one of the vloggers (pictured below). "It's not sexism. Women want it."

I asked him whether it felt strange to speak on behalf of women, considering he is a man.

"No. But there are more supporters for Protein World than against," he said. "Everyone's tired of feminism. I got into anti-feminist issues last year because every time I read the newspaper there's stuff about sexism. Somebody tried to sue somebody based on sexism and it was a lie."

He then told me he was filming me too, so I walked off.

Soon after, the protesters assembled in a shivering mass so they could pose for their very own beach body photograph. After that, there wasn't much else left to do, so everybody put their hoodies back on and started slowly sidling away.

Sandy and Sandra folded up their deck chair and left hand in hand; somebody started eating some macaroons; a girl accidentally burnt her tit with a cigarette; and that was that.

But while the protest was understated, the message was clear: advertisers, stop cashing in on making women feel like shit, you bunch of dead-eyed creeps.